The research in this Pediatric Oncology Program Project consists of four parts: 1) Bone Marrow Transplant. A new method has been devised for BMT and immunosuppression, which consists of total lymphoid irradiation rather than total irradiation. Because of this we have been able to do the last 7 A match non-infected aplastic anemia patients without any GVH, marrow rejection, interestitial pneumonitis or stomatitis. The median time in remission is over 8 months. 2) Platelet-Coagulation Studies. Extensive new knowledge has been developed in the study of platelets of chronic myelogenous leukemia. New endeavors relative to culturing megakarocytes are underway. 3) Cyclophosphamide. New techniques for measurement of cyclophosphamide and its metabolites have been developed. Repeated infusions of cyclophosphamide accelerate the activity and metabolism of cyclophosphamide. 4) Bone Marrow Culture Lab. Quantitative relationships between CFU-C and lymphocyte inhibition with treatment with ATG has been noted.